Biomedical subjects
W L Morison
Publications and source records attributed to W L Morison.
Phototherapy for children.
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Carcinogenicity of combined ultraviolet B radiation and psoralen plus ultraviolet A irradiation treatment of mice.
Psoralen plus ultraviolet A (PUVA) therapy and UVB phototherapy are frequently used in the treatment of psoriasis and other skin diseases. Both treatments are thought to be carcinogenic, but little is known about their interaction in the induction of skin cancer. Tumors induced in mice treated with both PUVA and UVB, either given sequentially or concurrently, seemed to be more antigenic as a group than tumors treated by PUVA alone, as determined by their lower frequency of growth when transplanted into naive mice. In this study, we treated C3H mice with a subcarcinogenic dose of UVB radiation for 4 weeks, followed by PUVA treatment for 41 weeks (sequential experiment) or with both UVB radiation (minimal carcinogenic dose) and PUVA for 41 weeks (concurrent experiment) and monitored the development of skin cancers. Although a few tumors appeared earlier in the groups treated with both UVB and PUVA in both experiments, no significant differences were observed in the rate of tumor development in mice treated with UVB and PUVA versus those treated with PUVA alone.
Sunlight: an environmental toxin for humans. A primer to advise patients.
Sunlight causes acute toxic effects such as sunburn, local and systemic immune suppression, and long-term adverse effects including photoaging and skin cancer. The degree of damage depends on the overall exposure-dose and individual susceptibility. Various strategies should be employed to minimize sun-exposure damage, including proper use of sunscreens and exposure avoidance. Public education might best be focused on protecting children and promoting awareness of photoaging changes in adults.